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gtp: fix wrong handling of option header fields in GTPv1 

TS 29.060 expresses thing is a quite complicated way just to say
that if any of the optional fields is there, then all optional
fields become mandatory :-).

"This field shall be present if and only if any one or more of the S,
PN and E flags are set.".

So, if any flag is set, we *always* have 4 extra bytes.
This commit is contained in:
Pablo Neira Ayuso 2014-03-18 17:27:32 +01:00
parent 151652cc80
commit 2cbf0a1483
1 changed files with 8 additions and 13 deletions
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21
gtp.c
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@ -260,17 +260,6 @@ out_rcu:
return ret;
}
static u8 gtp1u_header_len[] = {
[0] = 0, /* 0 */
[GTP1_F_SEQ] = 2, /* 2 */
[GTP1_F_NPDU] = 1, /* 1 */
[GTP1_F_SEQ|GTP1_F_NPDU] = 3, /* 2 + 1 */
[GTP1_F_EXTHDR] = 1, /* 1 */
[GTP1_F_EXTHDR|GTP1_F_SEQ] = 3, /* 1 + 2 */
[GTP1_F_EXTHDR|GTP1_F_NPDU] = 2, /* 1 + 1 */
[GTP1_F_EXTHDR|GTP1_F_NPDU|GTP1_F_SEQ] = 4, /* 1 + 1 + 2 */
};
static int gtp1u_udp_encap_recv(struct gtp_instance *gti, struct sk_buff *skb)
{
struct gtp1_header *gtp1;
@ -294,8 +283,14 @@ static int gtp1u_udp_encap_recv(struct gtp_instance *gti, struct sk_buff *skb)
if (gtp1->type != GTP_TPDU)
return 1;
/* look-up table for faster length computing */
hdrlen += gtp1u_header_len[gtp1->flags & GTP1_F_MASK];
/* From 29.060: "This field shall be present if and only if any one or
* more of the S, PN and E flags are set.".
*
* If any of the bit is set, then the remaining ones also have to be
* set.
*/
if (gtp1->flags & GTP1_F_MASK)
hdrlen += 4;
/* check for sufficient header size for extension */
if (!pskb_may_pull(skb, hdrlen))